CN113031417A

CN113031417A - Endless belt, transfer device, and image forming apparatus

Info

Publication number: CN113031417A
Application number: CN202010499059.5A
Authority: CN
Inventors: 田中宏晃; 杉浦聪哉; 种村大辅; 小野雅人; 古川雅士; 福田茂; 濑古真路; 松本晃一; 林圣悟; 铃木友子
Original assignee: Fujifilm Business Innovation Corp
Current assignee: Fujifilm Business Innovation Corp
Priority date: 2019-12-06
Filing date: 2020-06-04
Publication date: 2021-06-25
Also published as: JP7447452B2; JP2021092600A; US10996594B1

Abstract

The invention relates to an endless belt, a transfer device and an image forming apparatus. The endless belt is a single layer body comprising a layer of an imide resin and conductive particles or a laminated body having the layer as an outermost layer, and when a common logarithmic value of surface resistivity of an outer peripheral surface of the layer measured by using a ring probe under conditions of an applied voltage of 100V for 3 seconds and a load of 1kg is x (log Ω/□) and a common logarithmic value of volume resistivity of the layer measured by using a ring probe under conditions of an applied voltage of 100V for 5 seconds and a load of 1kg is y (log Ω cm), a value of y/x is 0.8992-1.0157 inclusive.

Description

Endless belt, transfer device, and image forming apparatus

Technical Field

The invention relates to an endless belt, a transfer device and an image forming apparatus.

Background

In an image forming apparatus (such as a copying machine, a facsimile machine, and a printer) using an electrophotographic method, a toner image formed on a surface of an image holding member is transferred onto a surface of a recording medium, and fixed on the recording medium to form an image. In the transfer of such a toner image to a recording medium, for example, a conductive endless belt such as an intermediate transfer belt is used.

For example, jp 2007-011117 a discloses "an intermediate transfer belt having at least a surface layer on a base material, wherein the surface layer contains aggregates of conductive particles having an average particle diameter of 0.5 to 25 μm".

Jp 2007 & 078789 a discloses "an intermediate transfer belt having at least a surface layer on a base material, wherein the surface layer contains metal-coated resin particles".

Disclosure of Invention

Technical problem to be solved by the invention

In an image forming apparatus using an endless belt as an intermediate transfer member, if a recording medium having large surface irregularities (hereinafter, also referred to as "irregular paper") such as embossed paper is used, the intermediate transfer member cannot follow the irregularities of the recording medium when a toner image is transferred from the intermediate transfer member to the recording medium, so that the transferability is lowered and white spots of the image may occur.

An object of the present invention is to provide an endless belt having excellent transferability to an uneven paper sheet when used as an intermediate transfer body, as compared with a case where the endless belt is a single-layer body including a layer having a y/x value of less than 0.8992 or more than 1.0157 and an electroconductive particle or a laminated body having the above-mentioned layer as an outermost layer.

Means for solving the problems

The above-described technical problem is solved by the following means.

According to the first aspect of the present invention, there is provided an endless belt which is a single layer body comprising a layer of an imide resin and conductive particles or a laminate body having the layer as an outermost layer, wherein when a common logarithmic value of surface resistivity of an outer peripheral surface of the layer measured with a ring probe under conditions of an applied voltage of 100V, an applied time of 3 seconds and a load of 1kg is x (log Ω/□), and a common logarithmic value of volume resistivity of the layer measured with a ring probe under conditions of an applied voltage of 100V, an applied time of 5 seconds and a load of 1kg is y (log Ω · cm), a value of y/x is 0.8992 or more and 1.0157 or less.

According to the invention of claim 2, the number average primary particle diameter of the conductive particles is 10nm or more and 20nm or less.

According to the 3 rd aspect of the present invention, the number average primary particle diameter of the conductive particles is 10nm or more and 15nm or less.

According to the 4 th aspect of the present invention, the conductive particles are carbon black having a ph of 2.0 or more and 3.0 or less.

According to claim 5 of the present invention, the carbon black is a channel black.

According to claim 6 of the present invention, the value of x is 9.0 to 13.0.

According to claim 7 of the present invention, the value of y is 8.2 to 13.0.

According to the 8 th aspect of the present invention, the imide resin is a polyimide resin.

According to the 9 th aspect of the present invention, the number average secondary particle diameter of the conductive particles is 1 to 8 times larger than the number average primary particle diameter of the conductive particles.

According to the 10 th aspect of the present invention, the endless belt is a single-layer body.

According to the 11 th aspect of the present invention, there is provided a transfer device comprising: an intermediate transfer member which is the endless belt; a primary transfer mechanism for primary-transferring the toner image formed on the surface of the image holding body to the surface of the intermediate transfer body; and a secondary transfer mechanism for secondary-transferring the toner image transferred to the surface of the intermediate transfer body to the surface of a recording medium.

According to the 12 th aspect of the present invention, there is provided an image forming apparatus comprising: an image holding body; a charging device for charging the surface of the image holding body; an electrostatic latent image forming device for forming an electrostatic latent image on the surface of the charged image holding member; a developing device that stores a developer containing a toner and develops an electrostatic latent image formed on a surface of the image holding member with the developer to form a toner image; and the transfer device that transfers the toner image to a surface of a recording medium.

Effects of the invention

According to the aspect 1,8, or 10, there is provided an endless belt having excellent transferability to an uneven paper when used as an intermediate transfer body, as compared with a case where the endless belt is a single-layer body including a layer having a y/x value of less than 0.8992 or more than 1.0157, or a laminated body having the layer as an outermost layer, the single-layer body including an imide resin and conductive particles.

According to the above aspect 2, there is provided an endless belt having excellent transferability to an uneven paper sheet when used as an intermediate transfer body, as compared with a case where the number average primary particle diameter of the conductive particles is larger than 20 nm.

According to the above aspect 3, there is provided an endless belt having excellent transferability to an uneven paper sheet when used as an intermediate transfer body, as compared with a case where the number average primary particle diameter of the conductive particles is larger than 15 nm.

According to the above aspect 4, there is provided an endless belt which is excellent in transferability to an uneven paper when used as an intermediate transfer body, as compared with a case where the conductive particles are carbon black having a pH of more than 3.0.

According to the above aspect 5, there is provided an endless belt having excellent transferability to an uneven paper when used as an intermediate transfer member, as compared with the case where the conductive particles are furnace black.

According to the above-mentioned aspect 6, there is provided an endless belt which is excellent in transferability to an uneven paper when used as an intermediate transfer body, as compared with the case where the value of x is less than 9.0 or more than 13.0.

According to the above 7 th aspect, there is provided an endless belt which is excellent in transferability to an uneven paper when used as an intermediate transfer body, as compared with the case where the value of y is less than 8.2 or more than 13.0.

According to the above 9 th aspect, there is provided an endless belt having excellent transferability to an uneven paper sheet when used as an intermediate transfer body, as compared with a case where the secondary particle diameter of the conductive particles is larger than 8 times the primary particle diameter of the conductive particles.

According to the 11 th aspect, there is provided a transfer device having excellent transferability to an uneven paper sheet, as compared with a case where an endless belt is used as an intermediate transfer body, and the endless belt is a single-layer body including a layer containing an imide-based resin and conductive particles and having a y/x value of less than 0.8992 or more than 1.0157, or a laminated body having the above-mentioned layer as an outermost layer.

According to the above 12 th aspect, there is provided an image forming apparatus having excellent transferability to an uneven paper, as compared with a case where an endless belt is used as an intermediate transfer body, and the endless belt is a single-layer body including a layer containing an imide-based resin and conductive particles and having a y/x value of less than 0.8992 or more than 1.0157, or a laminated body having the above layer as an outermost layer.

Drawings

Fig. 1 is a schematic configuration diagram showing an example of an image forming apparatus according to the present embodiment.

Detailed Description

The present embodiment will be explained below. The description and examples are intended to illustrate embodiments and are not intended to limit the scope of the embodiments.

In the numerical ranges recited in the present embodiment in stages, the upper limit value or the lower limit value recited in one numerical range may be replaced with the upper limit value or the lower limit value recited in another numerical range in another stage. In the numerical ranges described in the present embodiment, the upper limit or the lower limit of the numerical range may be replaced with the values shown in the examples.

The term "step" in the present embodiment includes not only an independent step but also a step that can achieve the intended purpose of the step even when the step cannot be clearly distinguished from other steps.

When the embodiments of the present embodiment are described with reference to the drawings, the configuration of the embodiments is not limited to the configuration shown in the drawings. The sizes of the components in the drawings are schematic, and the relative relationship between the sizes of the components is not limited to this.

Each component in the present embodiment may contain two or more corresponding substances. In the case where the amount of each component in the composition in the present embodiment is referred to, in the case where two or more species corresponding to each component are present in the composition, the total amount of the two or more species present in the composition is referred to unless otherwise specified.

[ endless band ]

The endless belt of the present embodiment is a single layer body of a layer including an imide resin and conductive particles or a laminated body having the layer as an outermost layer, and when a common logarithmic value of a surface resistivity of an outer peripheral surface of the layer measured using a ring probe under conditions of an applied voltage of 100V, an applied time of 3 seconds, and a load of 1kg is x (log Ω/□), and a common logarithmic value of a volume resistivity of the layer measured using a ring probe under conditions of an applied voltage of 100V, an applied time of 5 seconds, and a load of 1kg is y (log Ω cm), a value of y/x is 0.8992 or more and 1.0157 or less.

In the present specification, the term "conductivity" means that the volume resistivity at 20 ℃ is less than 1X 10¹³Ωcm。

Here, the measurement of the above-mentioned common logarithmic value x of the surface resistivity is performed by the following method.

A micro-ammeter (R8430A manufactured by advontest) was used as an electrical resistance measuring device, a UR probe (manufactured by mitsubishi chemical analysis) was used as a probe, and a common logarithmic value (log Ω/□) of the surface resistivity of the outer peripheral surface of the endless belt was measured under conditions of a voltage of 100V, an application time of 3 seconds, and a pressure of 1kgf, at 6 points in the circumferential direction at equal intervals on the outer peripheral surface of the endless belt, and at 3 points in the center portion and both end portions in the width direction, and at 18 points in total, and an average value was calculated. The measurement was performed at 22 ℃ and 55% RH.

The measurement of the above-mentioned usual logarithmic value y of the volume resistivity is carried out by the following method.

A micro-ammeter (R8430A manufactured by advontest) was used as a resistance measuring device, a UR probe (manufactured by mitsubishi chemical analysis) was used as a probe, and for a common logarithmic value (log Ω · cm) of the volume resistivity, the annular belt was measured at 6 points at equal intervals in the circumferential direction, and at 3 points at the center and both ends in the width direction, and 18 points in total, under conditions of a voltage of 100V, an application time of 5 seconds, and a pressure of 1kgf, and an average value was calculated. The measurement was performed at 22 ℃ and 55% RH.

In the present embodiment, when the endless belt is used as the intermediate transfer body, the transferability to the uneven paper is excellent by including the imide resin and the conductive particles in the single layer or the outermost layer and setting the y/x value to be 0.8992 or more and 1.0157 or less. The reason is not clear, and is presumed as follows.

In an image forming apparatus using an endless belt as an intermediate transfer body, when using an uneven paper as a recording medium, there may occur: when a toner image is transferred from the intermediate transfer body to the recording medium, the intermediate transfer body cannot follow the unevenness of the recording medium, so that the transferability is lowered, and white spots of the image occur.

Specifically, for example, in the secondary transfer region, the charge of the toner may flow out in the film thickness direction of the intermediate transfer body, and the charge amount of the toner may decrease, which may make it difficult to particularly perform transfer in the concave portion of the recording medium. Further, since it is difficult to form a sufficient transfer electric field in the concave portion of the recording medium, if the electric field at the time of transfer is increased, an excessive electric field is locally applied to the convex portion of the recording medium, and thus abnormal discharge occurs, and there is a possibility that the transferability is lowered due to a decrease in the charge amount of the toner or reverse charging.

In contrast, in the present embodiment, the single layer or the outermost layer contains the imide resin and the conductive particles, and the value of y/x is from 0.8992 to 1.0157. That is, although the volume resistivity of the conventional layer including the imide resin and the conductive particles is much lower than the surface resistivity, the single layer or the outermost layer in the present embodiment is a layer having a high volume resistivity while suppressing the surface resistivity to be lower than that of the conventional layer. Therefore, it is considered that the charge of the toner in the secondary transfer region is suppressed from flowing out in the film thickness direction of the intermediate transfer body, and the decrease in transferability due to the decrease in the charge amount of the toner is suppressed.

In addition, it is considered that in the layer containing the imide resin and the conductive particles and having the y/x value in the above range, the surface resistivity can be suppressed to be low and the distribution of the conductive particles in the thickness direction of the layer is small by finely dispersing the conductive particles on the outer peripheral surface, whereby the volume resistivity can be improved. Therefore, even if the intermediate transfer member cannot follow the unevenness of the recording medium and an excessive electric field is locally applied to the convex portion of the uneven paper, small electric discharges occur at the respective conductive points finely dispersed on the outer peripheral surface of the endless belt, and the electric current is dispersed, so that it is considered that the decrease in the amount of charge of the toner and the reverse charging due to the abnormal electric discharge are suppressed, and the transferability is improved.

For the above reasons, it is presumed that in the present embodiment, when the endless belt is used as the intermediate transfer member, the transferability to the uneven paper is excellent by including the imide resin and the conductive particles in the single layer or the outermost layer and by setting the value of y/x to 0.8992 or more and 1.0157 or less.

The annular belt may be a single-layer body or a laminated body.

When the endless belt is a single-layer body, the single-layer body contains an imide resin and conductive particles, and has a y/x value of 0.8992 to 1.0157.

When the endless belt is a laminate, the laminate includes, for example, a base material layer and a surface layer provided on the base material layer. The surface layer is the outermost layer of the endless belt. The laminate may have another layer between the base material layer and the surface layer.

When the endless belt is a laminate having a base material layer and a surface layer, the surface layer contains an imide resin and conductive particles, and has a y/x value of 0.8992 or more and 1.0157 or less. The substrate layer is not particularly limited, and examples thereof include a layer containing a resin for a substrate layer and conductive particles for a substrate layer.

Hereinafter, the layer of the endless belt as the single layer body is referred to as "single layer". In addition, the surface layer containing the imide resin and the conductive particles in the endless belt as a laminate is referred to as "layer 1", and the base layer containing the resin for the base layer and the conductive particles for the base layer is referred to as "layer 2". The imide-based resin and the conductive particles contained in the single layer or the 1 st layer are referred to as "the 1 st resin" and "the 1 st conductive particles", respectively, and the resin for the base layer and the conductive particles for the base layer contained in the 2 nd layer are referred to as "the 2 nd resin" and "the 2 nd conductive particles", respectively.

< resin >

The 1 st resin, i.e., the imide-based resin contained in the single layer or the 1 st layer, is a resin containing a structural unit having an imide bond, and examples thereof include a polyimide resin (PI resin), a polyamideimide resin (PAI resin), and the like. The 1 st resin more preferably contains a polyimide resin from the viewpoints of mechanical strength and dispersibility of the 1 st conductive particles. The 1 st resin may be composed of 1 kind of resin, or may be a mixture of 2 or more kinds of resins.

Examples of the 2 nd resin included in the 2 nd layer include a polyimide resin (PI resin), a polyamideimide resin (PAI resin), an aromatic polyether ether ketone resin, a polyphenylene sulfide resin (PPS resin), a polyether imide resin (PEI resin), a polyester resin, a polyamide resin, and a polycarbonate resin.

The 2 nd resin may be composed of 1 kind of resin, or may be a mixture of 2 or more kinds of resins.

When the endless belt has the 1 st layer and the 2 nd layer, the 1 st resin and the 2 nd resin may be the same resin or different resins, and preferably the same resin (for example, the 1 st resin and the 2 nd resin are both polyimide resins).

(polyimide resin)

Examples of the polyimide resin include imide compounds of polyamic acid (precursor of polyimide resin) which is a polymer of tetracarboxylic dianhydride and diamine compound.

Examples of the polyimide resin include resins having a structural unit represented by the following general formula (I).

[ solution 1]

In the general formula (I), R¹Represents a 4-valent organic group, R²Represents a 2-valent organic group.

As R¹Examples of the 4-valent organic group include an aromatic group, an aliphatic group, a cyclic aliphatic group, a group in which an aromatic group and an aliphatic group are combined, and a group in which these groups are substituted. Specific examples of the 4-valent organic group include residues of tetracarboxylic dianhydrides described later.

As R²Examples of the 2-valent organic group include an aromatic group, an aliphatic group, a cyclic aliphatic group, a group in which an aromatic group and an aliphatic group are combined, and a group in which these groups are substituted. Specific examples of the 2-valent organic group include residues of diamine compounds described later.

Specific examples of the tetracarboxylic acid dianhydride used as a raw material for the polyimide resin include pyromellitic acid dianhydride, 3,3 ', 4, 4' -benzophenonetetracarboxylic acid dianhydride, 3,3 ', 4, 4' -biphenyltetracarboxylic acid dianhydride, 2,3,3 ', 4-biphenyltetracarboxylic acid dianhydride, 2,3,6, 7-naphthalenetetracarboxylic acid dianhydride, 1,2,5, 6-naphthalenetetracarboxylic acid dianhydride, 1,4,5, 8-naphthalenetetracarboxylic acid dianhydride, 2' -bis (3, 4-dicarboxyphenyl) sulfone dianhydride, perylene-3, 4,9, 10-tetracarboxylic acid dianhydride, bis (3, 4-dicarboxyphenyl) ether dianhydride, and vinyltetracarboxylic acid dianhydride.

Specific examples of the diamine compound used as a raw material of the polyimide resin include 4,4 ' -diaminodiphenyl ether, 4 ' -diaminodiphenyl methane, 3 ' -dichlorobenzidine, 4 ' -diaminodiphenyl sulfide, 3 ' -diaminodiphenyl sulfone, 1, 5-diaminonaphthalene, m-phenylenediamine, p-phenylenediamine, 3 ' -dimethyl-4, 4 ' -biphenyldiamine, benzidine, 3 ' -dimethylbenzidine, 3 ' -dimethoxybenzidine, 4 ' -diaminodiphenyl sulfone, 4 ' -diaminodiphenyl propane, 2, 4-bis (β -amino-tert-butyl) toluene, bis (p- β -amino-tert-butylphenyl) ether, and the like, Bis (p-beta-methyl-delta-aminophenyl) benzene, bis-p- (1, 1-dimethyl-5-amino-pentyl) benzene, 1-isopropyl-2, 4-m-phenylenediamine, m-xylylenediamine, p-xylylenediamine, bis (p-aminocyclohexyl) methane, 1, 6-hexamethylenediamine, heptamethylenediamine, 1, 8-octamethylenediamine, 1, 9-nonanediamine, 1, 10-decanediamine, diaminopropyltetramethylene, 3-methylheptamethylenediamine, 4-dimethylheptamethylenediamine, 2, 11-diaminododecane, 1, 2-bis 3-aminopropoxyethane, 2-dimethylpropylenediamine, 3-methoxy-1, 6-hexamethylenediamine, 2, 5-dimethylheptamethylenediamine, 3-methylheptamethylenediamine, 5-methyl-1, 9-nonanediamine, 2, 17-diaminoeicosane (2,17- ジアミノエイコサデカン), 1, 4-cyclohexanediamine, 1, 10-diamino-1, 10-dimethyldecane, 12-diaminooctadecane, 2-bis [4- (4-aminophenoxy) phenyl ] octadecane]Propane, piperazine, H₂N(CH₂)₃O(CH₂)₂O(CH₂)NH₂、H₂N(CH₂)₃S(CH₂)₃NH₂、H₂N(CH₂)₃N(CH₃)₂(CH₂)₃NH₂And the like.

(Polyamide-imide resin)

Examples of the polyamideimide resin include resins having an imide bond and an amide bond in a repeating unit.

More specifically, the polyamideimide resin may be a polymer of a 3-valent carboxylic acid compound having an acid anhydride group (also referred to as tricarboxylic acid) and a diisocyanate compound or a diamine compound.

As tricarboxylic acids, trimellitic anhydride and its derivatives are preferred. In addition to tricarboxylic acids, tetracarboxylic dianhydrides, aliphatic dicarboxylic acids, aromatic dicarboxylic acids, and the like can be used in combination.

Examples of the diisocyanate compound include 3,3 '-dimethylbiphenyl-4, 4' -diisocyanate, 2 '-dimethylbiphenyl-4, 4' -diisocyanate, biphenyl-3, 3 '-diisocyanate, biphenyl-3, 4' -diisocyanate, 3 '-diethylbiphenyl-4, 4' -diisocyanate, 2 '-diethylbiphenyl-4, 4' -diisocyanate, 3 '-dimethoxybiphenyl-4, 4' -diisocyanate, 2 '-dimethoxybiphenyl-4, 4' -diisocyanate, naphthalene-1, 5-diisocyanate, naphthalene-2, 6-diisocyanate, and the like.

Examples of the diamine compound include compounds having the same structure as the isocyanate and having an amino group instead of the isocyanate group.

From the viewpoint of adjusting mechanical strength, volume resistivity, and the like, the content of the 1 st resin with respect to the entire single layer is preferably 60 mass% to 95 mass%, more preferably 70 mass% to 95 mass%, and still more preferably 75 mass% to 90 mass%.

From the viewpoint of adjusting mechanical strength, volume resistivity, and the like, the content of the 1 st resin with respect to the entire 1 st layer is preferably 60 mass% to 95 mass%, more preferably 70 mass% to 95 mass%, and still more preferably 75 mass% to 90 mass%.

From the viewpoint of adjusting mechanical strength, volume resistivity, and the like, the content of the 2 nd resin with respect to the entire 2 nd layer is preferably 60 mass% to 95 mass%, more preferably 70 mass% to 95 mass%, and still more preferably 75 mass% to 90 mass%.

< conductive particles >

Examples of the 1 st conductive particles contained in the single layer or the 1 st layer include carbon black, metals (e.g., aluminum, nickel, etc.), metal oxides (e.g., yttrium oxide, tin oxide, etc.), ion conductive materials (e.g., potassium titanate, LiCl, etc.), etc., and among them, carbon black is preferably used.

These conductive particles may be used alone in 1 kind, or two or more kinds may be used in combination.

Examples of the carbon black include ketjen black, oil furnace black, channel black (i.e., gas black), and acetylene black. As the carbon black, carbon black having a surface treated (hereinafter also referred to as "surface-treated carbon black") can be used.

The surface-treated carbon black is obtained by imparting a carboxyl group, a quinone group, a lactone group, a hydroxyl group, or the like to the surface thereof. Examples of the surface treatment method include: an air oxidation method in which a reaction is carried out by contacting with air in a high-temperature atmosphere; a method of reacting with nitrogen oxide or ozone at normal temperature (for example, 22 ℃); a method of oxidizing air at a high temperature and then oxidizing the air at a low temperature with ozone; and so on.

Among these, the conductive particles may be channel black, and particularly, acidic carbon black having a ph of 5.0 or less.

Examples of the acid carbon black include carbon black having an oxidized surface, for example, carbon black having a carboxyl group, a quinone group, a lactone group, a hydroxyl group, or the like provided on the surface.

The acid carbon black is preferably a carbon black having a ph of 4.5 or less, more preferably a carbon black having a ph of 4.0 or less, still more preferably a carbon black having a ph of 3.0 or less, particularly preferably a carbon black having a ph of 2.0 to 3.0, and most preferably a carbon black having a ph of 2.0 to 2.8, from the viewpoint of improving transferability to the uneven paper.

The pH of the acidic carbon black is measured by a pH measurement method specified in JIS Z8802 (2011).

The number average primary particle diameter of the 1 st conductive particles is, for example, in the range of 20nm or less, and is preferably in the range of 18nm or less, more preferably in the range of 15nm or less, and still more preferably in the range of 13nm or less, from the viewpoint of adjusting y/x to the above-mentioned range. The number average primary particle diameter of the 1 st conductive particles is, for example, in the range of 2nm or more, preferably in the range of 5nm or more, more preferably in the range of 10nm or more, from the viewpoint of adjusting y/x to the above range.

The number average primary particle diameter of the conductive particles was measured by the following method.

First, a measurement sample having a thickness of 100nm was taken from each layer of the obtained tape by a microtome, and the measurement sample was observed by TEM (transmission electron microscope). Then, the diameter of a circle (i.e., equivalent circle diameter) equal to the projected area of each of the 50 conductive particles was defined as a particle diameter, and the average value thereof was defined as a number average primary particle diameter.

The number average secondary particle diameter of the 1 st conductive particle is, for example, in the range of 13nm to 100nm, preferably in the range of 13nm to 55nm, more preferably in the range of 13nm to 40nm, from the viewpoint of adjusting y/x to the above range.

From the viewpoint of adjusting y/x to the above range, the number average secondary particle diameter of the 1 st conductive particles is preferably 1 to 8 times, more preferably 1 to 5 times, further preferably 1 to 4.5 times, particularly preferably 1 to 3.5 times, and very preferably 1 to 3 times the number average primary particle diameter of the 1 st conductive particles.

The number average secondary particle diameter of the conductive particles is determined from a 256-level gray scale image obtained by observing the outer peripheral surface of the endless belt with a scanning electron microscope (for example, model SU8010 manufactured by Hitachi High Technologies) at a magnification of 2 ten thousand times, and binarizing the image with a threshold value of 128. Specifically, the average value of the diameters of circles (i.e., equivalent circle diameters) equal to the projected areas of 50 individual particles such as the aggregate of the conductive particles is defined as the number average secondary particle diameter.

When the number average secondary particle diameter of the conductive particles includes primary particles existing alone without aggregation, an average value including the equivalent circle diameter of the primary particles existing alone is determined. That is, when all the conductive particles are present alone without being aggregated, the number average secondary particle diameter of the conductive particles is 1 time the number average primary particle diameter.

From the viewpoint of ensuring the resistance expression property and the surface dispersibility, the content of the 1 st conductive particle is preferably 10 mass% or more and 50 mass% or less, more preferably 12 mass% or more and 40 mass% or less, further preferably 14 mass% or more and 30 mass% or less, and particularly preferably 15 mass% or more and 20 mass% or less with respect to the entire monolayer.

From the viewpoint of ensuring the resistance expression property and the surface dispersibility, the content of the 1 st conductive particles with respect to the entire 1 st layer is preferably 10 mass% or more and 50 mass% or less, more preferably 12 mass% or more and 40 mass% or less, further preferably 14 mass% or more and 30 mass% or less, and particularly preferably 15 mass% or more and 20 mass% or less.

Specific examples of the 2 nd conductive particles included in the 2 nd layer include the same particles as those of the specific examples of the 1 st conductive particles, and preferred embodiments are also the same.

The number average primary particle diameter of the 2 nd conductive particles is, for example, in the range of 2nm to 40nm, preferably in the range of 20nm to 40nm, more preferably in the range of 20nm to 35nm, and still more preferably in the range of 20nm to 28nm in view of dispersibility, mechanical strength, volume resistivity, and the like.

From the viewpoint of adjusting dispersibility, mechanical strength, and volume resistivity, the content of the 2 nd conductive particles with respect to the entire 2 nd layer is preferably 5 mass% or more and 40 mass% or less, more preferably 10 mass% or more and 30 mass% or less, and further preferably 20 mass% or more and 30 mass% or less.

< other ingredients >

The single layer, the 1 st layer and the 2 nd layer may contain other components in addition to the resin and the conductive particles, respectively.

Examples of the other components include a conductive agent other than the conductive particles, a filler for improving the strength of the belt, an antioxidant for preventing thermal deterioration of the belt, a surfactant for improving fluidity, and a thermal aging inhibitor.

When other components are contained in the layer, the content of the other components is preferably more than 0% by mass and 10% by mass or less, more preferably more than 0% by mass and 5% by mass or less, and still more preferably more than 0% by mass and 1% by mass or less, based on the total mass of the target layer.

< characteristics of endless band >

(thickness of endless band)

The thickness of the single layer is preferably 60 μm to 120 μm, more preferably 80 μm to 120 μm, from the viewpoint of the mechanical strength of the tape.

From the viewpoint of production suitability and suppression of discharge, the thickness of the 1 st layer is preferably 1 μm to 40 μm, and more preferably 3 μm to 20 μm.

The thickness of the 2 nd layer is preferably 50 μm to 100 μm, more preferably 60 μm to 80 μm, from the viewpoint of the mechanical strength of the tape.

When the endless belt has the 1 st layer and the 2 nd layer, the ratio of the 1 st layer to the total thickness is preferably 3% to 50%, more preferably 5% to 30%, from the viewpoint of transferability to the uneven paper.

The film thickness of each layer was measured as follows.

That is, a cross section in the thickness direction of the endless belt is observed by an optical microscope or a scanning electron microscope, the thickness of the layer to be measured is measured at 10 places, and the average value thereof is defined as the thickness.

(volume resistivity and surface resistivity of endless band)

From the viewpoint of transferability to an uneven paper, a common logarithmic value y (log Ω · cm) of the volume resistivity in a single layer or the 1 st layer is preferably 8.2(log Ω · cm) to 13.0(log Ω · cm), more preferably 8.4(log Ω · cm) to 12.0(log Ω · cm), and particularly preferably 10.0(log Ω · cm) to 11.5(log Ω · cm).

From the viewpoint of transferability to the embossed paper, the common logarithmic value x (log Ω/□) of the surface resistivity of the outer peripheral surface in the single layer or the 1 st layer is preferably 9.0(log Ω/□) or more and 13.0(log Ω/□) or less, more preferably 9.0(log Ω/□) or more and 12.0(log Ω/□) or less, and particularly preferably 10.5(log Ω/□) or more and 11.5(log Ω/□) or less.

When the usual logarithmic value of the surface resistivity of the outer peripheral surface is in the above range, particularly, compared with the case where the value is higher than the above range, it is possible to suppress the charge from being easily attached to the single layer or the 1 st layer and to suppress the toner from being scattered.

The value of y/x is 0.8992 or more and 1.0157 or less, and is preferably 0.9000 or more and 1.0000 or less, more preferably 0.9300 or more and 1.0000 or less, and further preferably 0.9500 or more and 1.0000 or less, from the viewpoint of transferability to an uneven paper.

The method for setting the value of y/x in the above range is not particularly limited, and examples thereof include: a method of using particles having a small number average primary particle diameter as the 1 st conductive particles; a method of using carbon black having a low pH as the 1 st conductive particles; a method of selecting the kind of the 1 st conductive particles to be used; a method of adjusting conditions (e.g., drying conditions, etc.) in the manufacturing process of the endless belt; a method of combining them; and so on.

< method for producing endless Belt >

The method for manufacturing the endless belt of the present embodiment is not particularly limited.

In one example of the method for manufacturing the endless belt, for example, the following steps are performed: a 1 st coating liquid preparation step of preparing a 1 st coating liquid containing a 1 st resin or a precursor thereof, 1 st conductive particles, and a 1 st solvent; a 1 st coating film forming step of coating the 1 st coating liquid on the outer periphery of the material to be coated to form a 1 st coating film; and a 1 st drying step of drying the 1 st coating film while raising the temperature of the material to be coated. The above-described method for producing an endless belt may be subjected to other steps in addition to the 1 st coating liquid preparation step, the 1 st coating film formation step, and the 1 st drying step. As another step, for example, in the case of using the precursor of the 1 st resin, there may be mentioned a 1 st firing step of firing the 1 st coating film dried in the 1 st drying step.

In the case of manufacturing an endless belt as a single-layer body, a single layer containing the 1 st resin and the 1 st conductive particles is formed on the outer peripheral surface of the material to be coated by going through the 1 st coating liquid preparation step, the 1 st coating film formation step, and the 1 st drying step described above. The monolayer can be formed, for example, by preparing pellets containing the 1 st resin and the 1 st conductive particles and melt-extruding the pellets. The single layer may be formed by repeating the 1 st coating film forming step and the 1 st drying step 2 or more times to integrate 2 or more layers. The number of repetitions of the 1 st coating film forming step and the 1 st drying step is not particularly limited, and may be 2 or 3 or more.

In the case of manufacturing an endless belt as a laminate, for example, by undergoing the above-described 1 st coating liquid preparation step, 1 st coating film formation step, and 1 st drying step, the 1 st layer containing the 1 st resin and 1 st conductive particles is formed on the outer peripheral surface of the 2 nd layer formed on the material to be coated. The 1 st layer may be formed by repeating the 1 st coating film forming step and the 1 st drying step 2 or more times in the same manner as the single layer to integrate 2 or more layers.

In the case of manufacturing an endless belt as a laminated body, for example, the 2 nd layer is formed on the outer peripheral surface of the material to be coated by going through the following steps: a 2 nd coating liquid preparation step of preparing a 2 nd coating liquid containing a 2 nd resin or a precursor thereof, 2 nd conductive particles, and a 2 nd solvent; a 2 nd coating film forming step of forming a 2 nd coating film by applying the 2 nd coating liquid on an outer periphery of a material to be coated; and a 2 nd drying step of drying the 2 nd coating film. The 2 nd layer may be formed by, for example, preparing pellets containing the 2 nd resin and the 2 nd conductive particles and melt-extruding the pellets.

(coating liquid preparation step)

In the 1 st coating liquid preparation step, a 1 st coating liquid containing a 1 st resin or a precursor thereof, 1 st conductive particles, and a 1 st solvent is prepared. For example, in the case where the 1 st resin is a polyimide resin and the 1 st conductive particles are carbon black, as the 1 st coating liquid, for example, a solution in which carbon black is dispersed and polyamic acid that is a precursor of the polyimide resin is dissolved in the 1 st solvent is prepared. For example, when the 1 st resin is a polyamideimide resin and the 1 st conductive particle is carbon black, a solution in which carbon black is dispersed and the polyamideimide resin is dissolved in the 1 st solvent is prepared as the 1 st coating liquid.

As a method for preparing the coating liquid 1, from the viewpoint of pulverizing the aggregate of the conductive particles 1 and from the viewpoint of improving the dispersibility of the conductive particles 1, it is preferable to perform a dispersion treatment using a pulverizer such as a ball mill or a jet mill.

The 1 st solvent is not particularly limited, and may be appropriately determined depending on the kind of the resin used as the 1 st resin, and the like. For example, when the 1 st resin is a polyimide resin or a polyamideimide resin, the 1 st solvent is preferably a polar solvent described later.

Examples of the polar solvent include N-methyl-2-pyrrolidone (NMP), N-Dimethylformamide (DMF), N-dimethylacetamide (DMAc), N-diethylacetamide (DEAc), dimethyl sulfoxide (DMSO), hexamethylene phosphoramide (HMPA), N-methylcaprolactam, N-acetyl-2-pyrrolidone, 1, 3-dimethyl-2-imidazolidinone (N, N-dimethylimidazolidinone, DMI), and the like, and 1 kind thereof may be used alone or 2 or more kinds thereof may be used in combination.

In the case of being subjected to the 2 nd coating liquid preparation step, in the 2 nd coating liquid preparation step, the 2 nd coating liquid containing the 2 nd resin, the 2 nd conductive particles, and the 2 nd solvent is prepared. The 2 nd resin and the 2 nd conductive particles are as described above, and the method for preparing the 2 nd coating liquid and the 2 nd solvent are the same as the method for preparing the 1 st coating liquid and the 1 st solvent, respectively.

(coating film formation step)

In the 1 st coating film forming step, the 1 st coating liquid is applied to the outer periphery of the material to be coated to form a 1 st coating film.

Examples of the material to be coated include a cylindrical or columnar die. The material to be coated may be one obtained by treating the outer peripheral surface of the die with a release agent. In the case of manufacturing an endless belt as a single-layer body, in the 1 st coating film forming step, for example, the 1 st coating liquid is directly applied to the outer peripheral surface of the above-mentioned coating object or the coating object subjected to the releasing agent treatment. In the case of manufacturing an endless belt as a laminate, in the 1 st coating film forming step, for example, the 1 st coating liquid is applied to the outer peripheral surface of the material to be coated on which the 2 nd layer or the 2 nd coating film is formed.

Examples of the coating method of the first coating liquid 1 include known methods such as a spray coating method, a spiral coating (flow coating) method, a blade coating method, a wire rod coating method, a dip coating method, a bead coating method, an air knife coating method, and a curtain coating method.

In the case of being subjected to the 2 nd coating film forming step, in the 2 nd coating film forming step, the 2 nd coating liquid is applied on the outer periphery of the material to be coated to form the 2 nd coating film. The coating method of the 2 nd coating liquid is also the same as that of the 1 st coating liquid.

(drying step)

In the 1 st drying step, the 1 st coating film formed in the 1 st coating film forming step is dried. The 1 st solvent contained in the 1 st coating film is removed by the 1 st drying step to obtain a single layer or a 1 st layer.

Examples of the method for drying the 1 st coating film include a method of supplying hot air to the 1 st coating film, a method of heating a material to be coated, and the like.

The hot air velocity on the surface of the 1 st coating film is, for example, in the range of 0.1m/s to 50m/s, preferably in the range of 1m/s to 40m/s, and more preferably in the range of 1m/s to 20 m/s.

Here, the hot air speed on the surface of the 1 st coating film was measured as follows. Specifically, the velocity of the hot wind is obtained by connecting QB-5 of the attached wind speed and wind temperature probe ( pay FENG velocity-FENG temperature 12503; \12525 ーブ) to MONITOR-N and converting the output voltage value according to a conversion equation.

The hot air temperature on the surface of the 1 st coating film is, for example, in the range of 100 ℃ to 280 ℃, preferably in the range of 100 ℃ to 250 ℃, and more preferably in the range of 110 ℃ to 235 ℃.

The hot air temperature on the surface of the No. 1 coating film was measured by connecting a thermometer (e.g., Graphtec K thermocouple, model: JBS-7115-5M-K) to Graphtec data recorder (model: GL 240).

The method of supplying hot air to the surface of the 1 st coating film is not particularly limited, and examples thereof include a method of blowing hot air in a drying furnace from a slit nozzle toward the surface of the 1 st coating film, a method of directly supplying hot air in a drying furnace to the 1 st coating film, and the like. Among these, the method using a slit nozzle is preferable in terms of easily controlling the speed of hot air on the surface of the 1 st coating film.

Note that, in the case of being subjected to the 2 nd drying step, in the 2 nd drying step, the 2 nd coating film formed by the 2 nd coating film forming step is dried. The method of drying the 2 nd coating film is the same as the method of drying the 1 st coating film. The 2 nd drying step may be completed before the 1 st coating film forming step is performed, or the 1 st coating film forming step may be performed before the 2 nd drying step is completed, so that the 1 st drying step also serves as a part of the 2 nd drying step.

(firing step)

As described above, the manufacturing method of the endless belt may be subjected to the 1 st firing step. In the 1 st firing step, firing is performed by heating the 1 st coating film dried by the 1 st drying step. For example, in the case where the 1 st resin is a polyimide resin, the polyamic acid contained in the 1 st coating film is imidized by the 1 st firing step to obtain a polyimide.

The heating temperature in the 1 st firing step is, for example, in the range of 150 ℃ to 450 ℃, preferably 200 ℃ to 430 ℃. The heating time in the 1 st firing step is, for example, in the range of 20 minutes to 180 minutes, preferably 60 minutes to 150 minutes.

In the case of manufacturing an endless belt as a laminate, when the 2 nd layer is formed by undergoing the 2 nd coating liquid preparation step, the 2 nd coating film formation step, and the 2 nd drying step, the 2 nd firing step of firing the 2 nd coating film dried by the 2 nd drying step may be performed. The 2 nd firing step may double as the 1 st firing step.

[ transfer device, image Forming apparatus ]

The transfer device of the present embodiment includes: an intermediate transfer body; a primary transfer mechanism for primary-transferring the toner image formed on the surface of the image holding body to the surface of the intermediate transfer body; and a secondary transfer mechanism that secondarily transfers the toner image transferred to the surface of the intermediate transfer body to the surface of the recording medium, and the transfer device of the present embodiment uses the above-described endless belt as the intermediate transfer body.

The image forming apparatus of the present embodiment includes: an image holding body; a charging device for charging the surface of the image holding body; an electrostatic latent image forming device for forming an electrostatic latent image on the surface of the charged image holding member; a developing device that stores a developer containing a toner and develops an electrostatic latent image formed on a surface of the image holding member with the developer to form a toner image; and a transfer device that transfers the toner image onto a surface of a recording medium, and the image forming apparatus of the present embodiment uses the transfer device as a transfer device.

An example of the image forming apparatus according to the present embodiment will be described below with reference to the drawings.

Fig. 1 is a schematic configuration diagram showing a configuration of an image forming apparatus according to the present embodiment.

The endless belt is applied as an intermediate transfer belt.

In the image forming apparatus of the present embodiment, for example, a portion including at least the transfer device may be configured such that an ink cartridge (process cartridge) is attachable to and detachable from the image forming apparatus.

As shown in fig. 1, an image forming apparatus 100 according to the present embodiment is an image forming apparatus of an intermediate transfer system generally called a tandem type, for example, and includes: a plurality of

image forming units

1Y,1M,1C,1K for forming toner images of respective color components by an electrophotographic method; a primary transfer section 10 (i.e., a primary transfer area) for sequentially transferring (primary transferring) the toner images of the respective color components formed by the

image forming units

1Y,1M,1C, and 1K to the intermediate transfer belt 15; a secondary transfer portion 20 (i.e., a secondary transfer area) that collectively transfers (secondary transfers) the superposed toner images transferred onto the intermediate transfer belt 15 to a sheet K as a recording medium; and a fixing device 60 for fixing the image after the secondary transfer to a sheet K (an example of a recording medium). Further, the image forming apparatus 100 includes a control unit 40 that controls the operation of each apparatus (each unit).

Each of the

image forming units

1Y,1M,1C, and 1K of the image forming apparatus 100 includes a photoconductor 11 (an example of an image holder) that rotates in the direction of arrow a as an example of an image holder for holding a toner image formed on a surface.

Around the photoreceptor 11, a charger 12 for charging the photoreceptor 11 is provided as an example of a charging device, and a laser exposure device 13 (an exposure beam is denoted by a symbol Bm in the drawing) for writing an electrostatic latent image on the photoreceptor 11 is provided as an example of an electrostatic latent image forming device.

Further, around the photoconductor 11, as an example of a developing device, a developing device 14 for storing toner of each color component and forming a visible image of an electrostatic latent image on the photoconductor 11 with toner is provided, and a primary transfer roller 16 for transferring the toner image of each color component formed on the photoconductor 11 to an intermediate transfer belt 15 by a primary transfer portion 10 is provided.

Further, around the photoconductor 11, a photoconductor cleaner 17 for removing residual toner on the photoconductor 11 is provided, and a charger 12, a laser exposure device 13, a developing device 14, a primary transfer roller 16, and the photoconductor cleaner 17 are arranged in this order along the rotation direction of the photoconductor 11. These

image forming units

1Y,1M,1C,1K are arranged in a substantially linear shape in the order of yellow (Y), magenta (M), cyan (C), and black (K) from the upstream side of the intermediate transfer belt 15.

The intermediate transfer belt 15 as an intermediate transfer body has a volume resistivity of, for example, 1 × 10⁶1 × 10 at a height of Ω cm¹⁴Omega cm or less, and the thickness thereof is, for example, about 0.1 mm.

The intermediate transfer belt 15 is circularly driven (rotated) in the B direction shown in fig. 1 at a speed suitable for the purpose by various rollers. The various rollers include the following rollers: a drive roller 31 that is driven by a motor (not shown) having an excellent constant speed to rotate the intermediate transfer belt 15; a support roller 32 that supports the intermediate transfer belt 15 extending substantially linearly along the arrangement direction of the photosensitive members 11; a tension applying roller 33 that applies tension to the intermediate transfer belt 15 and functions as a correcting roller for preventing meandering of the intermediate transfer belt 15; a back roller 25 provided in the secondary transfer section 20; the cleaning back roller 34 is provided in a cleaning section for scraping off residual toner on the intermediate transfer belt 15.

The primary transfer section 10 is constituted by a primary transfer roller 16 disposed so as to face the photoreceptor 11 with the intermediate transfer belt 15 interposed therebetween. The primary transfer roller 16 is disposed in pressure contact with the photoreceptor 11 so as to sandwich the intermediate transfer belt 15, and a voltage (primary transfer bias) having a polarity opposite to the charging polarity (negative polarity, the same applies hereinafter) of the toner is applied to the primary transfer roller 16. Thereby, the toner images on the respective photoconductors 11 are sequentially electrostatically attracted to the intermediate transfer belt 15, and a toner image superimposed on the intermediate transfer belt 15 is formed.

The secondary transfer section 20 includes a back roller 25 and a secondary transfer roller 22 disposed on the toner image holding surface side of the intermediate transfer belt 15.

The back roller 25 has a surface resistivity of 1X 10⁷1 × 10 above omega/□¹⁰Omega/□, and the hardness is set to 70 DEG (ASKER C: KOBUNSHI KEIKI CO., LTD. manufactured by LTD., the same applies hereinafter). The back roller 25 is disposed on the back side of the intermediate transfer belt 15, constitutes the counter electrode of the secondary transfer roller 22, and is disposed in contact with a metal power supply roller 26 that stably applies a secondary transfer bias.

On the other hand, the secondary transfer roller 22 has a volume resistivity of 10^7.510 above omega cm^8.5ΩcA cylindrical roll of m or less. The secondary transfer roller 22 is disposed in pressure contact with the back roller 25 so as to sandwich the intermediate transfer belt 15, and the secondary transfer roller 22 is grounded to form a secondary transfer bias with the back roller 25 to secondarily transfer the toner image to the sheet K conveyed to the secondary transfer unit 20.

The conveying speed of the sheet K in the secondary transfer unit 20 is, for example, in a range of 50mm/s to 60 mm/s.

An intermediate transfer belt cleaner 35 is provided on the downstream side of the secondary transfer section 20 of the intermediate transfer belt 15 so as to be freely detachable from and contactable with the intermediate transfer belt 15, and removes residual toner and paper dust on the intermediate transfer belt 15 after the secondary transfer to clean the surface of the intermediate transfer belt 15.

The intermediate transfer belt 15, the primary transfer section 10 (primary transfer roller 16), and the secondary transfer section 20 (secondary transfer roller 22) correspond to an example of a transfer device.

On the other hand, a reference sensor (home position sensor) 42 is disposed upstream of the yellow image forming unit 1Y, and the reference sensor (home position sensor) 42 generates a reference signal as a reference for controlling the image forming timing in each of the

image forming units

1Y,1M,1C, 1K. Further, an image density sensor 43 for adjusting image quality is disposed downstream of the black image forming unit 1K. The reference sensor 42 is configured as follows: the marks provided on the back side of the intermediate transfer belt 15 are recognized, a reference signal is generated, and the

image forming units

1Y,1M,1C, and 1K start image formation in response to the recognition of the reference signal and an instruction from the control unit 40.

Further, the image forming apparatus according to the present embodiment includes, as a transport mechanism for transporting the sheet K: a sheet storage section 50 that stores sheets K; a paper feeding roller 51 for taking out and conveying the paper K accumulated in the paper storage unit 50 at a predetermined timing; a conveying roller 52 that conveys the sheet K fed out by the paper feed roller 51; a conveying guide 53 that feeds the sheet K conveyed by the conveying roller 52 to the secondary transfer portion 20; a conveying belt 55 that conveys the sheet K conveyed after secondary transfer by the secondary transfer roller 22 to the fixing device 60; the paper K is guided to the fixing inlet guide 56 of the fixing device 60.

Next, a basic image forming process of the image forming apparatus of the present embodiment will be described.

In the image forming apparatus of the present embodiment, image data output from an image reading apparatus, a Personal Computer (PC), or the like, not shown, is subjected to image processing by an image processing apparatus, not shown, and then image forming jobs are executed by the

image forming units

1Y,1M,1C, and 1K.

The image processing apparatus performs image processing such as various image editing such as shading correction, positional offset correction, luminance/color space conversion, γ correction, frame elimination, color editing, and motion editing on the input reflectance data. The image data subjected to the image processing is converted into color material gradation data of 4 colors Y, M, C, K, and is output to the laser exposure device 13.

In the laser exposure unit 13, an exposure light beam Bm emitted from, for example, a semiconductor laser is irradiated to each of the photoreceptors 11 of the

image forming units

1Y,1M,1C, and 1K based on the input toner gradation data. In each of the photoreceptors 11 of the

image forming units

1Y,1M,1C, and 1K, after the surface is charged by the charger 12, the surface is scanned and exposed by the laser exposure device 13 to form an electrostatic latent image. The formed electrostatic latent images are developed by the respective

image forming units

1Y,1M,1C,1K in the form of toner images of the respective colors of Y, M, C, K.

The toner images formed on the photoreceptors 11 of the

image forming units

1Y,1M,1C,1K are transferred onto the intermediate transfer belt 15 at the primary transfer portions 10 where the photoreceptors 11 are in contact with the intermediate transfer belt 15. More specifically, in the primary transfer section 10, a voltage (primary transfer bias) having a polarity opposite to the charging polarity (negative polarity) of the toner is applied to the base material of the intermediate transfer belt 15 by the primary transfer roller 16, and the toner images are sequentially superimposed on the surface of the intermediate transfer belt 15 to perform primary transfer.

The toner images are sequentially primary-transferred onto the surface of the intermediate transfer belt 15, and then the intermediate transfer belt 15 is moved to convey the toner images to the secondary transfer unit 20. When the toner image is transferred to the secondary transfer unit 20, the feed roller 51 is rotated in the transfer mechanism according to the timing of transferring the toner image to the secondary transfer unit 20, and the paper K of the target size is supplied from the paper storage unit 50. The sheet K fed by the sheet feeding roller 51 is conveyed by the conveying roller 52, and reaches the secondary transfer unit 20 via the conveying guide 53. Before reaching the secondary transfer unit 20, the position of the sheet K and the position of the toner image can be positioned by temporarily stopping the sheet K and rotating a registration roller (not shown) according to the timing of movement of the intermediate transfer belt 15 holding the toner image. Even when a paper having irregularities on the surface, such as embossed paper, is used as the paper K, good transferability to the paper K can be obtained.

In the secondary transfer section 20, the secondary transfer roller 22 is pressed against the back roller 25 via the intermediate transfer belt 15. At this time, the paper sheet K conveyed according to the timing is sandwiched between the intermediate transfer belt 15 and the secondary transfer roller 22. At this time, when a voltage (secondary transfer bias) having the same polarity as the charging polarity (negative polarity) of the toner is applied by the power feeding roller 26, a transfer electric field is formed between the secondary transfer roller 22 and the back roller 25. After that, the unfixed toner image held on the intermediate transfer belt 15 is electrostatically transferred to the sheet K together at the secondary transfer portion 20 pressurized by the secondary transfer roller 22 and the back roller 25.

Thereafter, the sheet K to which the toner image is electrostatically transferred is directly conveyed in a state of being peeled off from the intermediate transfer belt 15 by the secondary transfer roller 22, and is conveyed to the conveyor belt 55 provided on the downstream side of the secondary transfer roller 22 in the sheet conveying direction. In the conveying belt 55, the sheet K is conveyed to the fixing device 60 according to an optimum conveying speed in the fixing device 60. The unfixed toner image on the sheet K conveyed to the fixing device 60 is subjected to a fixing process under heat and pressure by the fixing device 60, thereby being fixed on the sheet K. Thereafter, the sheet K on which the fixed image is formed is conveyed to a discharged sheet storage unit (not shown) provided in a discharge unit of the image forming apparatus.

On the other hand, after the transfer to the paper K is completed, the residual toner remaining on the intermediate transfer belt 15 is conveyed to the cleaning portion with the rotation of the intermediate transfer belt 15, and is removed from the intermediate transfer belt 15 by the cleaning back roller 34 and the intermediate transfer belt cleaner 35.

The present embodiment has been described above, but the present embodiment is not to be construed as being limited to the above embodiment, and various modifications, alterations, and improvements can be made.

Examples

Examples of the present invention will be described below, but the present invention is not limited to the following examples. In the following description, "part" and "%" are all based on mass unless otherwise specified.

[ example 1]

Preparation of coating solution

To an N-methyl-2-pyrrolidone (NMP) solution of polyamic acid formed from 3,3 ', 4,4 ' -biphenyltetracarboxylic dianhydride and 4,4 ' -diaminodiphenyl ether (the solid content fraction after imide conversion is 18 mass%), carbon black particles (channel black, FW200, Orion Engineered Carbons) were added in an amount of 19.0 parts by mass per 100 parts by mass of the solid content of polyamic acid, and the mixture was mixed and stirred to prepare coating solution 1 as a carbon black-dispersed polyimide precursor solution.

Production of intermediate transfer belts

An aluminum cylinder having an outer diameter of 278mm and a length of 600mm was prepared.

While the aluminum cylindrical body was rotated, coating liquid 1 was discharged to the outer surface of the aluminum cylindrical body at a width of 500mm by a dispenser (dispenser) to form a coating film having a thickness of 80 μm.

Then, the aluminum cylindrical body on which the coating film was formed was heated and dried at 140 ℃ for 30 minutes in a state in which the cylindrical body was horizontal, and then heated for 120 minutes so that the maximum temperature reached 320 ℃, thereby obtaining an endless belt.

Then, the axial center portion of the endless belt was cut to a width of 363mm, to obtain an intermediate transfer belt 1.

[ example 2]

An intermediate transfer belt 2 was obtained in the same manner as in example 1, except that the amount of carbon black particles added was changed from 19.0 parts by mass to 17.5 parts by mass in the preparation of the coating liquid.

[ example 3]

An intermediate transfer belt 3 was obtained in the same manner as in example 1, except that the amount of carbon black particles added was changed from 19.0 parts by mass to 20.0 parts by mass in the preparation of the coating liquid.

[ example 4]

An intermediate transfer belt 4 was obtained in the same manner as in example 1 except that 14.0 parts by mass of carbon black particles (channel black, FW285, Orion Engineered Carbons) were added in place of 19.0 parts by mass of the carbon black particles (FW200) in preparation of the coating liquid.

[ example 5]

An intermediate transfer belt 5 was obtained in the same manner as in example 1 except that 14.0 parts by mass of carbon black particles (channel black, FW182, Orion Engineered Carbons) were added in place of 19.0 parts by mass of the carbon black particles (FW200) in preparation of the coating liquid.

[ example 6]

An intermediate transfer belt 6 was obtained in the same manner as in example 1, except that the amount of carbon black particles added was changed from 19.0 parts by mass to 20.1 parts by mass in the preparation of the coating liquid.

[ example 7]

An intermediate transfer belt 7 was obtained in the same manner as in example 1, except that the amount of carbon black particles added was changed from 19.0 parts by mass to 17.4 parts by mass in the preparation of the coating liquid.

Comparative example 1

An intermediate transfer belt C1 was obtained in the same manner as in example 1, except that 27.5 parts by mass of carbon Black particles (channel Black, Special Black4, Orion Engineered Carbons) were added in place of 19.0 parts by mass of the carbon Black particles (FW200) in the preparation of the coating liquid.

[ measurement of intermediate transfer Belt ]

The intermediate transfer belt thus obtained was measured for a common logarithmic value x (log Ω/□) of the surface resistivity and a common logarithmic value y (log Ω · cm) of the volume resistivity of the outer peripheral surface by the above-described methods. The results are shown in Table 1.

Table 1 shows the layer structure of the endless belt, the number average primary particle diameter (nm) of the carbon black particles used, and the pH of the carbon black particles used.

The number average secondary particle diameter R of the conductive particles (carbon black particles) was obtained by the above method for the obtained intermediate transfer belt, and the ratio (R/R) to the number average primary particle diameter R was calculated. The results are shown in Table 1.

[ evaluation of intermediate transfer Belt ]

< evaluation of transferability to embossed paper >

The obtained intermediate transfer belt was attached to a belt (Iridose) incorporated in an image forming apparatus^TMProduction Press, manufactured by fuji schle) to perform image quality evaluation.

In the image quality evaluation, the evaluation was performed using embossed paper (Lesac 66, 250gsm) using a K-color (i.e., black) halftone 60% solid image. The evaluation criteria are as follows, and the results are shown in table 1.

Evaluation criteria-

A: almost no white spots were exposed in the recesses of the paper

B: slightly exposed in the concave part of the paper

C: about half of the paper is exposed to white

D: most of the concave parts of the paper are exposed to white

[ Table 1]

From the results shown in table 1, it is understood that the belt of the present example is superior in transferability even when a recording medium having large surface irregularities is used, as compared with the belt of the comparative example.

Claims

1. An endless belt which is a single-layer body or a laminate body,

the layer of the single layer body contains an imide resin and conductive particles, and when a common logarithmic value of surface resistivity of the outer peripheral surface of the layer measured with a ring probe under conditions of an applied voltage of 100V, an applied time of 3 seconds, and a load of 1kg is defined as x log Ω/□, and a common logarithmic value of volume resistivity of the layer measured with a ring probe under conditions of an applied voltage of 100V, an applied time of 5 seconds, and a load of 1kg is defined as y log Ω · cm, a value of y/x is 0.8992-1.0157,

the laminate is a laminate having the above-mentioned layer as the outermost layer.

2. The endless belt according to claim 1, wherein the number average primary particle diameter of said conductive particles is 10nm or more and 20nm or less.

3. The endless belt according to claim 2, wherein the number average primary particle diameter of said conductive particles is 10nm or more and 15nm or less.

4. The endless belt according to any one of claims 1 to 3, wherein said conductive particles are carbon black having a pH of 2.0 or more and 3.0 or less.

5. The endless belt of claim 4 wherein said carbon black is channel black.

6. The endless belt according to any one of claims 1 to 5, wherein the value of x is 9.0 or more and 13.0 or less.

7. The endless belt according to any one of claims 1 to 5, wherein the value of y is 8.2 or more and 13.0 or less.

8. The endless belt according to any one of claims 1 to 7, wherein said imide resin is a polyimide resin.

9. The endless belt according to any one of claims 1 to 8, wherein a number average secondary particle diameter of the conductive particles is 1 to 8 times larger than a number average primary particle diameter of the conductive particles.

10. The endless belt as claimed in any one of claims 1 to 9 wherein the endless belt is a single layer.

11. A transfer device is provided with:

an intermediate transfer body which is the endless belt according to any one of claims 1 to 10,

a primary transfer mechanism for primary-transferring the toner image formed on the surface of the image holding body onto the surface of the intermediate transfer body, an

And a secondary transfer mechanism for secondary-transferring the toner image transferred to the surface of the intermediate transfer body to a surface of a recording medium.

12. An image forming apparatus includes:

an image holding body is provided on the image holding body,

a charging device for charging the surface of the image holding body,

an electrostatic latent image forming device for forming an electrostatic latent image on the surface of the charged image holding body,

a developing device for storing a developer containing a toner, developing the electrostatic latent image formed on the surface of the image holding member with the developer to form a toner image, and

the transfer device according to claim 11, wherein the toner image is transferred to a surface of a recording medium.